Dancing Wings S.E.5.a 1/10 scale biplane build

[tudordewolf]

Got the itch for biplanes recently and this kit caught my eye for cheap. Having built one of their foam/ply planes before, I figured it'd be a nice "break" and a fun first biplane. It has been one of the most technically challenging builds I've ever done.

It uses a classic wood frame for the fuselage. I always love piecing these together and seeing a sturdy 3D shape come to life from the delicate wood features. The manual suggests piecing it together then just zapping all the joints with super glue, but I like to go slow and use wood glue & clamp any wood-to-wood connections, it's just... so much better.

You then 'skin' it with pre-printed ~3mm foamboard, which is tricky to position and glue without breaking any of the features underneath. To get it to line up with the holes it needs to match on either side of the fuselage, I had to gently "stretch" it over the curved portion. I accomplished this by marking the foam & gluing the center first, then doing the sides:

You can see in this pic the degree of stretch, kind of a cool, "canvas" effect, just so tricky to work with...

It uses a similarly interesting hybrid structure for the wing. Wood ribs form the airfoil shape, carbon fiber rods provide stiffness, and that same printed foam-board as on the fuselage forms the skin and remaining structure of the wing. Much like the body, getting it glued and lined up is pretty difficult, while keeping the wing straight. Ironically the first few sections I did came out pretty well, I can even see straight through the holes in the ribs of the top wing all the way through to the other side, and then the very last one, a lower section, came out so twisted I've ordered a second kit just to finish the first one properly. Given the time invested, It's worth it at this point.

To make the leading edge curve fit the ribs, I had to cut out a relief groove from the back of the foam (not in the instructions, my own addition), without slicing all the way through: (I did in a few places, a bit of tape on the outside patches it up fine)

Tiny wing servo mount, a 4.3g servo:

I added some reinforcement, not even full stringers but just strips cut from the scrap ply, to the portion of the fuselage where the tail begins, it felt like too little structure at a crucial section of the plane. After of that part it gets "denser" and everything is closer together so its less flimsy, though I did snap that one tombstone-shaped piece at the right of the image 3 separate time, before assembly, during assembly, and once after while wiring the servos.

The tail is another marathon of challenges: you need to cut the bevel for the control surfaces into the 5mm foamboard yourself:

And use a torque rod to actuate the split tail using only one servo link:

Making the elevators work with that was its own challenge, it won't just slide into the foam, it tears it if you try. I wound up having to drill them with a 1.5mm bit, I used my tiny drill press to keep it straight, but I don't see how they expect people to pull that off on their first try. I thought I snapped a pic but can't find it.


You also need to cut slots for hinges into the foam yourself, a task made substantially easier by the vicious looking slot hinger:

And prepare the tail for the rudder by cutting away excess foam:

But once it all comes together, it is pretty rewarding seeing the bevels you cut allowing the swivel of the rudder.

The stock power setup recommends a 2212 motor, 20A ESC, and a 1300mAh battery, all of which I found a bit heavy-sounding for a plane this size. I spent entirely too long on https://rcplanes.online/calc_motor.htm trying to find a more optimized solution, until inspiration struck - this little 800kv, 30g motor will produce 450g of thrust on only 6A of current, spinning an APC 9x3.7SF prop, as verified by my highly sophisticated test equipment:

That, with a little 'XP-12A" ESC, cuts 70g of weight, 18g from the motor and 10g from the ESC, (an ounce on the powerplant alone), and another 40g cut from the battery with an 850mah 3S. I haven't flown it yet, but I'm excited to see how it performs.

From this angle you can almost pretend it's not missing a wing...

 

[CertifiedMike]

I am super impressed by the details! Looks like a super hard build but I am not a plane builder
It looks amazing! I hope we see it in the air soon!

 

[Lucifur10]

Way cool! Would take about 10 times the patience that I could muster.

 

[Doom!]

Very cool! I used to have a Parkzone SE5, not nearly as complex as this, but bi-planes feel a lot different in the air. One thing tricky about the SE5 is it has narrow landing gear, which makes it a bit wobbly on landings, causing the wingtips to drag. Easy does it, especially if landing on a hard surface.

 

[Hobbydude2]

SE-5

 

[tudordewolf]

SE-5

https://www.nationalmuseum.af.mil/V...Sheets/Display/Article/197391/eberhart-se-5e/

I'm just going with what the manufacturer labels it for anyone who may be making one themselves and searching for it online. Admittedly, "S.E.5.a" is incorrect, it should be "5a", and the SE-5E designation came later.

 

[tudordewolf]

Very cool! I used to have a Parkzone SE5, not nearly as complex as this, but bi-planes feel a lot different in the air. One thing tricky about the SE5 is it has narrow landing gear, which makes it a bit wobbly on landings, causing the wingtips to drag. Easy does it, especially if landing on a hard surface.

Appreciate it, looked that one up and it looks like it was a neat plane, a bit bigger, and that one used an 1800mah 3s and weighed twice as much with a 37" wingspan, so I think it stands to reason that size battery would be pretty heavy for this one to lug around, with only 30" wingspan.

The landing gear on this one isn't the scale-accurate struts, rather just a bent aluminum strap with a wide stance and some tall, skinny wheels which look like they'll make it grass-field capable even at 1lb AUW.

 

[WickedFog]

Awesome man! Thanks for sharing! I love this kinda stuff.

 

[Lukedavis]

This is so cool! Thanks for sharing!

 

[Hobbydude2]

https://www.nationalmuseum.af.mil/V...Sheets/Display/Article/197391/eberhart-se-5e/

I'm just going with what the manufacturer labels it for anyone who may be making one themselves and searching for it online. Admittedly, "S.E.5.a" is incorrect, it should be "5a", and the SE-5E designation came later.

Its British.

 

[tudordewolf]

Used some colored sharpies to do the bare foam edges & inside the hinge lines:

Some more info about the motor: it's a 2405 800kv or 850kv motor (I'm pretty sure there's only one kind, it's just ambigious which is the correct spec), unbranded, and advertised as doing 500g @7A on 3S with an 8x4.8SF, so I figured that was a good current limit to stay within. With an 8x3.8SF, I read 400g thrust on only 5.5A, which is quite impressive.

The original design has the motor behind the firewall, shaft poking through, no provisions made for airflow, but it's running a low kv motor that could take 6S in the right application on only 3S, so it's probably not an issue thermally... Just not very efficient design-wise.

I mounted this one to the front since it was 2/3rds the weight and with a lighter battery it would need more "leverage" to bring the CG forward, this also addresses the cooling issues, doubly so because I drilled extra holes behind the motor which will ventilate the ESC and battery compartment much more effectively than before.

The ESC it was sold with is pretty nifty too, the "XP-12A", weighs only 11g with cables, and can handle up to 3S @ 12A, almost 150W from an ESC the size of a micro-receiver. On top of that, it has a 5V/1A BEC onboard, though it is linear (guess they ran out of room for a buck converter), so every watt of power you want from it is a watt of heat wasted & added to the ESC. The servos I'm using have stall currents of about 300mA, so it is ideal for a few 4.3g servos or below, but 9g servos would probably be too much.

I suspect that as small as it is, the majority of its cooling happens through conduction with the wires attached to it.

Speaking of, it uses 2mm banana plugs and a JST-RCY connector, perfectly appropriate for its amp needs, which saves yet more weight compared to the XT60 and 3.5mm bullet plugs of a generic 20A ESC, and correspondingly higher-gauge wires.

 

[WickedFog]

That is looking SOOO cool!

 

[tudordewolf]

Continued geek out about the motor:

To simulate it, within prop calc I've found that the closest match is the Neumotors 2508 O/6/806 , chosen for having a kv between 800 and 850 and a weight close to the motor (~30g). The himax 2212 850kv also comes close, but I found the real world values closer to the aforementioned choice.

Being able to swing a 9" prop on 3S at only 30g motor weight seems uncommon, most slow fly/3D planes seem to use a 2S setup and less power overall in a lighter plane to spin their slow-fly props.

To that end, I'm near the upper limit of slow-fly prop RPM, around 7k RPM out of 7.2k given APC's formula (65k/diameter inches). I believe with the slow fly props it's not so much about safety as efficiency, past that limit they flex too much to still be optimal and a stiffer propeller should be chosen. The pitch speed is a tad low at 25mph, but the plane will hopefully be floaty enough to work with that. I can't imagine its minimalist structure holding up to much more than that, anyway.

Another advantage of the front-faced mounting is the propeller being held slightly out in front of the fuselage, wasting less thrust to the blocked area since there is a slightly conical "throw" to the propeller's backwash.

A final bonus is that the 9" prop is very close to scale-accurate, the real-world one having a 2.36M propeller, so 9"=228mm is as close as I can get unless APC releases a 9.25" SF prop just for this plane. Fitting wasn't easy though, it's made for a 5.5mm shaft and doesn't include any centering rings for other sizes, apparently that's standard in the indoor 3D world, but I needed it to fit a 5mm mandrel mount, so I used a thin wrap of electrical tape I snipped away a cm at a time until it just started to fit, them tightened the nose cone on and it spun smoothly.

 

[Edfrombama]

Good afternoon-
This is excellent. I have much the same kit and I am not ready to start in on building, but your account of the build helps me visualize the process much better than the printed instructions.

Now, a question. What sort of radio receiver does this kit use? I tend to stick to Spectrum stuff, but I do not know if it would work with this receiver.

Again, many thanks for your post- most appreciated.

Ed

 

[tudordewolf]

Good afternoon-
This is excellent. I have much the same kit and I am not ready to start in on building, but your account of the build helps me visualize the process much better than the printed instructions.

Now, a question. What sort of radio receiver does this kit use? I tend to stick to Spectrum stuff, but I do not know if it would work with this receiver.

Again, many thanks for your post- most appreciated.

Ed

Good luck and let us know how it goes! The exact same kit, or another one like it, like their PT-19? Looks like the same build concepts were used for that one.

You'll need a 4-channel receiver, so for Spektrum an AR410 would be a good choice.

I'm using Radiolink so I've got an R6DS in mine. Feel free to ask any questions you have during the build, or if you even need some spare parts, I'll have everything but a lower-left wing extra from the second kit I bought.

One of the hardest parts is the lower wings because the tabs for the struts poke up in a way that prevents you from smoothly "rolling" the foam against the surface of your table to smooth out the wing, and the servo sticks out of the bottom. The holes for the tabs fit in theory, but don't have enough give to let them fit through while you're actually wrapping the foam, so if you haven't cut them slightly longer (you can leave the material) you'll find yourself trying to squish little wood tabs through holes that barely line up while the whole thing is coated in super-glue and quickly becoming unworkable.

I think I'll use two notebooks to create a little space for those tabs, and then roll the wing down so they fall between them and I can press the rest of the wing "flat"

For some of the tricky-to-glue details, like the tail foam which has to line up with the wood servo mounts + tail openings, I've started using 2-part epoxy (BSI 15 minute) thinned with a few drops of denatured alcohol (no more than 20% per mfg website). This gives me the time to position the foam, while with super-glue you basically get one chance to stick it down, maybe shift it a little, and then it sets hard and makes a mess that only gets worse if you have to lift and re-glue it. For bits that didn't glue fully down, I dab a little foam safe glue onto a toothpick and swipe it under/between the details and pinch them together.